The incubation period or latency period is the amount of time between being exposed to a contagious disease and when you begin developing symptoms.

This is not the same as the contagious period or the time during which your child can get others sick.

Incubation Period

Depending on the disease, the incubation period can be just a few hours or can last for several months. Knowing the incubation period for a disease can help you understand if your child is still at risk of getting sick or if he is in the clear — whether he is exposed to someone with strep throat, measles, or the flu.

“The incubation period is the time from exposure to the causative agent until the first symptoms develop and is characteristic for each disease agent.”

CDC

It can also help you figure out where and when your child got sick. For example, if your infant develops chickenpox, a vaccine-preventable disease, you can’t blame it on your cousin who doesn’t vaccinate her kids and who was visiting just three days ago. The incubation period for chickenpox is at least 10 to 21 days. So your child who is too young to be vaccinated likely caught chicken pox from someone he was exposed to a few weeks ago.

As we saw in recent outbreaks of Ebola and measles, a diseases incubation period can also help you figure out how long an exposed person needs to stay in quarantine. After all, if they don’t get sick once the incubation period is over, then they likely won’t get sick and can be released from quarantine.

Incubation Periods of Childhood Diseases

The incubation period for some common diseases includes:

Adenovirus – 2 to 14 days, leading to a sore throat, fever, and pink eye

vomiting after exposure to Bacillus cereus, a type of food poisoning – 30 minutes to 6 hours (short incubation period

Knowing the incubation period of an illness isn’t always as helpful as it seems, though, as kids often have multiple exposures when kids around them are sick, especially if they are in school or daycare.

Conditions with long incubation periods can also fool you, as you might suspect a recent exposure, but it was really someone your child was around months ago.